The overarching aim of this proposal is to empirically research the common and unique ingredients of behavior, cognitive and brief dynamic psychotherapy. The long-term objective is to improve the efficacy of these three most widely employed psychotherapy modalities, so that a greater percentage of treated individuals could both obtain and maintain therapeutic benefits. In this proposal, we wish to study the additive and interactive contribution to outcome of two key components of the psychotherapeutic process, that is, the alliance and the therapist interventions. Furthermore, we aim to identify the therapist interventions which could enhance the status of the alliance and contribute to premature termination. This proposal will draw on an already conducted comparative clinical trial of behavior (n = 30) cognitive (n = 31), and brief dynamic therapy (n = 30), which were found to be equally effective for treating depression (NIMH Grant R01MH37196). The sample is composed of older adults who were diagnosed at intake as having a Major Depression Disorder. An array of outcome variables were measured at intake, termination and follow-up moments, which reflect both general symptomatology and adjustment, as well as the specific target criteria of each treatment condition. In this study, two teams of trained clinical judges will independently rate either the alliance on the California Psychotherapy Alliance Scale (CALPAS; Marmar & Gaston, 1988) or the therapist interventions on the Inventory of Therapeutic Strategies (ITS; Gaston, 1988). These two measures were previously found to be reliably rated and to be potentially valid. Measurements will be taken at time points representing early, middle, and late phases of therapy. During the study, recalibration sessions will be conducted periodically to counter rater drift, and the reliability of CALPAS ant ITS ratings will be assessed using intraclass correlation ICC[2,4]. Hypotheses will be tested using an hierarchical regression approach in which problems of multicollinearity will be prevented against. The planned analyses possess sufficient power to adequately test the specified hypotheses. Statistical significance and percentage of outcome variance accounted for will be both considered to support each hypothesis.